the first explosion two men are seen walking toward the finish line carrying largeknapsacks,tamerlantsarnaevis in front and dzhokhar tsarnaev is a few feet behind. the two are seen a half block away from a restaurant camera. a minute later, bomber one, tamerlan walks out of the crowd with a knapsack on his back. at 2:45, alleged bomber two, dzhokhar walks to the finish line. he has a cell phone in his left hand. the affidavit says he stops near a metal barrier his back to the cameras and he is apparently slipping his knapsack on the ground. he stands there for four minutes, looking at his cell phone appearing to take a picture and a deadly final 30 seconds. just before the first explosion, dzhokhar tsarnaev lifts the phone to his ear as if speaking on it. for 18 seconds he keeps the phone to his ear. as he appears to finish his call the crowd reacts to the first explosion. virtually every head turns toward the blast except for tsarnaev who virtually alone among the individuals appears calm. he glances to the east and starts walking rapidly to the west away from the finish line with

, and also what you would expect him to say, the olderbrother,tamerlan, wasthe driving force behind these terrorist attacks. based on what the investigators are getting from dzhokhar, this government sore tells me that the brothers, according to dzhokhar, seem to be self-radicalized, self-starters. they were motivated by the driving train of thought was jihadist thought. and all the governments -- i'm sorry all the political or religious implications that entails the idea being, of course, that they thought they construed islam to be under attack and needed to fight back. that's what they're saying based on initial interviews, preliminary interviews with dzhokhar. >> where he's speaking, communicating by writing, by hand signals, nodding? >> not speaking. communicating through nodding, through writing and other ways of nonverbal. he has that bullet wound to his throat. he can't really speak. he spoke one word in that interview with the magistrate yesterday. >> no. >> he said no. and the magistrate said let the record reflect that i believe the defendant, the suspect, is saying no. h

the attack. the brutal killing of oneoftamerlantsarnaev'sbest friends unsolved since 2011 is now being reviewed with a, quote, wider group of eyes. we'll show you a controlled explosion of a pressure cooker bomb as experts work to learn all they can about these cheap and deadly devices. i'm wolf blitzer in boston and you're in "the situation room." here in boston investigators are learning more about the suspects in last week's bloody massacres. here are the latest developments. a government official tells cnn the surviving suspect told investigators the wars in afghanistan and iraq were motivating factors in the attacks. a new hampshire fireworks store confirms tamerlan tsarnaev bought two reloadable mortar kits with 48 shells but law enforcement officials say it wasn't enough for explosions of the size that occurred in boston. an 8-year-old bombing victim martin richard was buried today after a private funeral mass. his parents issued a statement saying, and i'll read it to you, we laid our son martin to rest and he is now at peace. just minutes ago the sisters of the bombing suspect

just been answer announced. >>> also, boston bombingsuspecttamerlantsarnaev'sreported outburst at a cambridge, massachusetts, mosque. what set him off. >>> and was it a sign that he was turning radical? and is there a connection between one of the alleged bombers and militants in his native russia? cnn is on the ground there. we're looking for answers. i'm wolf blitzer. this is a special edition of "the situation room." >> announcer: this is cnn breaking news. >> and the breaking news coming in from canada right now where authorities have just announced the arrest as of two men believed to be part of an al qaeda-supported plot to attack a passenger train, a train potentially heading to the united states. they say the suspects were receiving support from al qaeda elements in iran. we want to stress, though, the u.s. government sources saying this plot is in no way related to the terror attacks that occurred one week ago here in boston at the boston marathon. let's go straight to cnn international security correspondent paula newton in ottawa, canada. she has the very latest. tel

of which exploded during the thursday night battle that ended with the deathoftamerlantsarnaev.his brother, the younger brother, was captured in watertown last night and he lies seriously wounded right now in a local hospital. a justice department official says he will face federal terrorism charges, possibly state murder charges at the same time. we are learning the 19-year-old was at the university of massachusetts dartmouth, just south of boston, every day, yes, every day after the attack. late thursday, he attended classes as well as dorm parties. hard to believe, but that's what we are learning right now. in the tense final standoff, dzhokhar tsarnaev was hidden in a bo a boat parked in the watertown driveway of a resident covered by a tarp. a helicopter overhead was able to take what they call thermal images showing the movements inside that boat. joining us now is tom foreman, national security analyst, tom fuentes as well, assistant former director of the fbi. these thermal images, walk us through, tom, what was going on. >> we were just talking about this a moment ago, wol

tamerlanafew years ago. >>> this morning we heard from their mother obviously distraught over what happened. here is what she said. >> what's happened is a terrible thing. i know my kids had nothing to do with this. i know it. i am mother. i know my kids. i know my kids. really my kids would never get involved into anything like that. >> nick paton walsh is in dagestan with us. before i bring him in, i want to show a little bit of that interview. >> do you believe what he was told? >> they're being accused because they were muslims. nothing else. >> reporter: do you think they'll get a fair trial? >> i don't know. >> nick paton walsh joins me now. you also had a lengthy phone conversation with her. do how recently she lived with her sons? she says she knows them well, but do we know how often she was actually living in the home? >> reporter: i believe they were together in the united states for a period of six months. quite a bit of overlapping, but mostly what i heard in that phone call a deeply distraught woman that finally realized that it was her son that had been killed. she s

actually flee the vehicles and start shooting back at the officers olderbrothertamerlanputshis cruiser in gear so it begins to roll down the street. as is he out there firpg officers empty the rounds. able to move in on him and capture him. >> bill: i understand they were in very close quarters and they shot tamerlan he was shot a number of times, right? >> yes, yes, yes. he was struck by bullets. it's unclear when he suffered the fatal injuries because as they are struggling with him. as they are trying to arrest him and handcuff him, he is resisting arrest, his brother shoots out with the suv. his brother got into the suv and drives into the scene and drives into the brother. >> runs him over? >> runs him over and carries him several feet with the car. >> and the police dove out of the way. one police officer was shot, right, in the shootout not only was tamerlan shot but a cop was shot as well, right? >> a transit police officer by the name of richard donahue was shot in the leg, suffered a very serious injury but is recovering thank god. >> so then the younger, the 19-year-old he d

to keep an eye on the olderone,tamerlan, gointerview. the f.b.i. did talk to him in 2011 and they cleared him. they said this guy has been scrubbed. he's okay. >>alisyn: they assessed he had not become radicalized even though it sound like russian authorities thought he had. for some reason there was a red flag they raised. they let him go. >> not totally clear it was the russians, because the australians may have had questions about this guy as well. some foreign government asked us to check him out. we did. didn't find anything wrong. then they dropped the ball on their end too. >>alisyn: we're going to be talking to so many experts this morning and brick all the new developments -- and bringing all the new developments kofplgt up, he is captured, in custody. the 19-year-old suspect has not been read his miranda rights. we'll tell you what that means as our breaking news coverage continues. stay with us. ♪ using supercomputing and mobile technology over our secure network, verizon innovators are building a world of medical treatment data in the cloud. so doctors can m